Digital camera including the compression of size-reduced images after picture taking is completed

ABSTRACT

A digital camera includes a CCD imager. In a successive picture-taking mode, each time a subject is taken by the CCD imager, a corresponding main image signal is compressed by a JPEG CODEC. The compressed main image signals produced upon each picture taking are accumulated in a SDRAM. A compression process of thumbnail image signals is performed after completing successive picture taking by the CCD imager. That is, each of the compressed main image signals secured in the SDRAM is decompressed by the JPEG CODEC, a thumbnail image signal is produced on the basis of a decompressed image signal so that a produced thumbnail image signal is compressed by the JPEG CODEC. When all the compressed thumbnail image signals are produced, each of a compressed main image signal and compressed thumbnail image signal is recorded onto a memory card.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to digital cameras and, moreparticularly, to a digital camera which records, to a recording medium,in a compressed state of main and size-reduced image signalscorresponding to respective images of a subject taken successively.

2. Description of the Prior Art

According to DCF (Design rule for Camera File system), there is a needof producing thumbnail image signals in addition to main image signalsso that both the image signals are recorded in a compressed state to arecording medium. Consequently, in the conventional digital camera, themain image signal is first compressed and then the thumbnail imagesignal produced from the main image signal is compressed so that bothcompressed signals are recorded to a recording medium. Meanwhile, duringsuccessive picture taking, totally-twice compression processes of mainand thumbnail image signals must be waited for taking the next picture.After completing the last-time picture taking, all the compressedsignals are recorded to the recording medium.

However, during successive picture taking, the picture-taking intervalincreases if the next picture taking is commenced after twice ofcompression processes have been done. It would be possible to shortenthe picture-taking interval by compressing both the main and thumbnailimage signals after completing successive picture taking. This howeverresults in increase in the capacity of an internal memory.

SUMMARY OF THE INVENTION

Therefore, it is a primary object of the present invention to provide adigital camera capable of reducing the picture-taking interval duringsuccessive shooting and suppresses the capacity of an internal memory.

According to the present invention, a digital camera for recording, in acompression state, a plurality of main image signals and a plurality ofsize-reduced image signals that correspond to a plurality ofsuccessively taken subject images to a recording medium, comprises: amain image compressor for compressing one of the main image signals eachtime picture taking is made once; and a size-reduced image compressorfor compressing the plurality of size-reduced image signals after endingsuccessive taking of pictures.

When a subject is successively taken of pictures, a plurality of mainimage signals and a plurality of size-reduced image signals are producedcorresponding to a plurality of subject images successively taken. Theseimage signals thus produced are recorded in a compressed state to arecording medium. Here, compression of the main signals is made by amain image compressor while compression of the size-reduced imagesignals is by a size-reduced image compressor. However, the main imagecompressor compresses one main image signal each time picture taking ismade once, and the size-reduced image compressor compresses a pluralityof size-reduced image signals after ending the successive picturetaking.

Because a plurality of size-reduced image signals are compressed afterending successive picture taking in this manner, it is possible toshorten the picture-taking interval. Also, because the main image signalis compressed each time picture taking is made once, it is possible tosuppress the capacity of an internal memory.

In one embodiment of the invention, a plurality of compressed main imagesignals produced by the main image compressor are temporarily held by amemory. When the successive picture taking is ended, a size-reducedimage producer produces the plurality of size-reduced image signals onthe basis of the plurality of compressed main image signals held by thememory after ending the successive taking of pictures. The size-reducedimage compressor compresses the plurality of size-reduced image signalsproduced by the size-reduced image producer.

The size-reduced image producer includes a decompressor and a thinner.The decompressor decompresses the plurality of compressed main imagesignals held by the memory and the thinner performs thinning out on aplurality of decompressed main image signals produced by thedecompressor and produce the plurality of size-reduced image signals.

In another embodiment of the invention, a size-reduced image producerproduces one of the size-reduced image signals each time picture takingis made once. The size-reduced image signals produced by thesize-reduced image producer are temporarily held the memory. Thesize-reduced image compressor compresses a plurality of size-reducedimage signals held by the memory after ending the successive taking ofpictures.

The above described objects and other objects, features, aspects andadvantages of the present invention will become more apparent from thefollowing detailed description of the present invention when taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a configuration of one embodiment ofthe present invention;

FIG. 2 is a flowchart showing part of operation of the FIG. 1embodiment;

FIG. 3 is an illustrative view showing a configuration of anotherembodiment of the invention; and

FIG. 4 is a flowchart showing part of operation of the FIG. 3embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, a digital camera 10 of this embodiment includes aCCD imager (image sensor) 12. The CCD imager 12 has a light-receivingsurface covered by a color filter (not shown) so that an optical imageof a subject is illuminated through the color filter onto thelight-receiving surface.

When an operator switches a mode-selector switch 37 to a “CAMERA” side,the system controller 36 establishes a camera mode. Thereupon, the CPU32 instructs a timing generator (TG) 14 to perform thinning-out readingso that the CCD imager 12 is driven in the thinning-out reading schemeby the TG 14. Due to this, low-resolution camera signals (pixel signals)corresponding to the subject image are outputted from the CCD imager 12.

The output camera signal is subjected to well-known noise removal andlevel adjustment in a CDS/AGC circuit 16 and then converted into adigital signal by an A/D converter 18. A signal processing circuit 20produces a YUV signal on the basis of the A/D-converted camera signaland supplies the produced YUV signal together with a write request to amemory control circuit 22. The YUV signal is written to an SDRAM 24 by amemory control circuit 22.

On the other hand, a video encoder 26 sends a read request to the memorycontrol circuit 22. The memory control circuit 22 reads a YUV signalfrom the SDRAM 24 in response to that request. The video encoder 26fetches the YUV signal thus read-out and converts the fetched YUV signalinto a composite image signal. The converted composite image signal isoutputted onto a monitor 28. As a result, real-time motion images(through-images) of the subject is displayed on the monitor 28.

When a shutter button 38 is pressed in a state that asuccessive-picture-taking mode on-off switch 40 is set to an “OFF” side,the system controller 36 outputs a corresponding control signal. At thistime, a CPU 32 instructs the TG 14 to perform all-pixel reading. The TG14 drives the CCD imager 12 in the all-pixel reading scheme on aone-screen-period basis. Due to this, a high-resolution camera signal inone screen is outputted from the CCD imager 12. That is, picture takingof a subject is made once, and a camera signal corresponding to a takensubject image is outputted from the CCD imager 12. The output camerasignal is processed similarly to the above and a high-resolution YUVsignal is secured within the SDRAM 24.

Note that a high-resolution YUV signal obtained by operating the shutterbutton 38 is hereinafter defined as a main image signal. Also, the mainimage signal is secured in a main image area 24 a of the SDRAM 24.

The CPU 32 also instructs a JPEG CODEC 30 to compress the main imagesignal in timing of storing the main signal to the SDRAM 24. Responsiveto a given compression command, the JPEG CODEC 30 first requests thememory control circuit 22 to read out a main image signal. The memorycontrol circuit 22 reads a main image signal out of the main image area24 a in response to this read request and sends a read main image signalto the JPEG CODEC 30. The JPEG CODEC 30 performs JPEG compression on themain image signal to thereby produce a compressed main image signal.Producing the compressed main image, the JPEG CODEC 30 provides thecompressed main image signal, together with a write request, to thememory control circuit 22. The compressed main image signal is stored toa compressed image area 24 c of the SDRAM 24 by the memory controlcircuit 22.

After storing the compressed main image signal to the SDRAM 24, the CPU32 instructs the memory control circuit 22 to perform thinning-out onthe main image signal secured within the main image area 24 a. Thememory control circuit 22 performs vertical thinning-out and horizontalthinning-out processes on the main image signal in response to thatinstruction and creates a thumbnail image signal. The created thumbnailimage signal is stored in a thumbnail image area 24 b.

After creating a thumbnail image signal, the CPU 32 instructs the JPEGCODEC 30 to compress the thumbnail image signal. The JPEG CODEC 30requests the memory control circuit 22 to read out a thumbnail imagesignal in response to the compression instruction and then performs JPEGcompression on a read-out thumbnail image signal. After producing acompressed thumbnail image signal, the JPEG CODEC 30 provides thiscompressed thumbnail image signal, together with a write request, to thememory control circuit 22. The compressed thumbnail image signal isstored to the compressed image area 24 c by the memory control circuit22.

After securing the compressed main image signal and compressed thumbnailimage signal within the SDRAM 24 in this manner, the CPU 32 sends a filepreparing command and read request to the memory control circuit 22. Thememory control circuit 22 first prepares an image file conforming to DCFin response to the file preparing instruction. In this image file isaccommodated a compressed main image signal and compressed thumbnailimage signal obtained by the above process. The memory control circuit22 subsequently reads an image file out of the SDRAM 24 in response to aread request and provides a read-out image file to the CPU 32. The CPU32 records the image file given from the memory control circuit 22 ontoa memory card 34.

When the shutter button 40 is pressed in a state that asuccessive-picture-taking mode is set by thesuccessive-picture-taking-mode on-off switch 42, successive picturetaking is performed by the CCD imager 12. Main image signals andthumbnail image signals corresponding to respective subject images thustaken are recorded in a compressed state to the memory card 34. At thistime, the CPU 32 processes a flowchart shown in FIG. 2.

Referring to FIG. 2, when the shutter button 38 is pressed, the CPU 32in step S1 first sets a count value of a counter 32 a to “1” and then,in step S3, instructs the TG14 to perform all-pixel reading. The TG 14drives the CCD imager 12 in the all-pixel reading scheme therebyoutputting a high-resolution camera signal in one screen from the CCDimager 12. That is, the subject is taken once due to once of all-pixelread instruction, and a camera signal corresponding to a picture-takensubject image is outputted from the CCD imager 12. The outputhigh-resolution camera signal is processed similarly to the above. As aresult, a main image signal in one screen is secured in the main imagearea 24 a of the SDRAM 24.

The CPU 32, in step S5, subsequently instructs the JPEG CODEC 30 tocompress the main image signal. The JPEG CODEC 30 outputs a read requestto the memory control circuit 22 in response to this instruction andperforms JPEG compression on the main image signal read by the memorycontrol circuit 22. The JPEG CODEC 30 also outputs the compressed mainimage signal produced by the JPEG compression, together with a writerequest, to the memory control circuit 22. The compressed main imagesignal is stored to the compressed image area 24 c of the SDRAM 24 bythe memory control circuit 22.

The CPU 32 advances to step S7 in timing that the compressed main imagesignal is secured in the compressed image area 24 c, to compare acurrent count value N of the counter 32 a with a predetermined value M(M: the number of pictures successively taken). Here, if the count valueN has not reached the predetermined value M, the CPU 32 proceeds to stepS9 and increments the counter 32 a in this step, then returning to thestep S3. This result in execution of M times a series of processes oftaking a picture of a subject by the CCD imager 12, producing a mainimage signal corresponding to the taken subject image and compressingthe produced main image signal. Thus, compressed main image signals inthe number of M are secured within the compressed image area 24 c.

When the count value N reaches the predetermined value M, the CPU 32 instep S7 determines “YES” and proceeds to processes of step S11 and thefollowing. At first, in step S11, “1” is set to the counter 32 a. Then,in step S13, the JPEG CODEC 30 is instructed to decompress a compressedimage signal corresponding to the current count value N. The JPEG CODEC30 requests the memory control circuit 22 to read out Nth-producedcompressed main image signal and performs JPEG decompression on acompressed main image signal read out of the compressed image area 24 c.The JPEG CODEC 30 furthermore requests the memory control circuit 22 towrite the produced decompressed main image signal. The decompressed mainimage signal is written to the main image area 24 a of the SDRAM 24 bythe memory control circuit 22.

The CPU 32 advances to step S15 in timing that the decompressed mainimage signal is written to the SDRAM 24 and, in this step, instructs thememory control circuit 22 to perform thinning-out on the decompressedmain image signal. The memory control circuit 22 performs thinning-outon the decompressed main image signal stored in the main image area 24 ato create a thumbnail image signal and stores a created thumbnail imagesignal to the thumbnail image area 24 b.

After creating the thumbnail image signal, the CPU 32 advances to stepS17 to instruct the JPEG CODEC 30 to compress the created thumbnailimage signal. The JPEG CODEC 30 requests the memory control circuit 22to read a thumbnail image signal and performs JPEG compression on a readthumbnail image signal. Obtaining a compressed thumbnail image signal,the JPEG CODEC 30 outputs the compressed thumbnail image signal togetherwith a write request to the memory control circuit 22. The compressedthumbnail image signal is stored in the compressed image area 24 c bythe memory control circuit 22. That is, both the Nth-produced compressedmain image signal and the corresponding thumbnail image signal aresecured within the compressed image area 24 c.

The CPU 32 in the succeeding step S19 sends a file preparing instructionto the memory control circuit 22. The memory control circuit 22 preparesan image file conforming to DCF in the compressed image area 24 c, inresponse to the instruction. In this image file, the Nth compressedimage signal and the Nth thumbnail image signal will be accommodated.

In step S21, the current count value N is compared to a predeterminedvalue M. If N<M, the counter 32 a in step S23 is incremented and thenthe process returns to the step S13. Due to this, the process of stepsS13 to S23 is repeated until the count value N reaches the predeterminedvalue M. That is, each compressed main image signal stored in thecompressed image area 24 c is subjected to JPEG decompression. Based onthe decompressed main image signal, a thumbnail image signal isproduced. The thumbnail image signal is subjected to JPEG compression.Then, the compressed main image signal and compressed thumbnail imagesignal in mutual correspondence is accommodated in a common image file.Image files in the number of M are obtained in the compressed image area24 c.

When the count value N reaches the predetermined value M, the CPU 32advances to step S25 to record the image files in the number of M storedin the compressed image area 24 c to the memory card 34. That is, thememory control circuit 22 is requested to read out image files so thatthe image files read out by the memory control circuit 22 are recordedonto the memory card 34. After recording all the image files, the CPU 32returns to the main routine (not shown).

According to this embodiment, each time the image sensor takes onepicture of a subject, a compression process on the corresponding mainimage signal is made. On the other hand, the compression process of thethumbnail image signal is first performed after ending the successivetaking of pictures. Specifically, after securing the compressed mainimage signals in the number of M within the memory, each of thecompressed main image signals is decompressed so that a thumbnail imagesignal is produced on the basis of the decompressed image signal. Then,a compression process is performed on the thumbnail image signals in thenumber of M.

Because the compressed thumbnail image signals are produced after endingthe successive taking of pictures in this manner, it is possible toshorten the picture-taking interval of the image sensor. Also, thecompression of main image signals in timing of between picture takingenables to reduce the internal memory capacity.

Referring to FIG. 3, a digital camera 10 of another embodiment has athinning-out circuit 20 a provided in the signal processing circuit 20so that the thinning-out circuit 20 a can produce thumbnail imagesignals from main image signals. Consequently, the operation afterpressing the shutter button 30, in any of setting and not setting thesuccessive picture-taking mode, is different from that of the FIG. 1 toFIG. 2 embodiment. However, the through-image display process beforepressing the shutter button 38 is the same as that of the FIG. 1 to FIG.2 embodiment. Hence, the through-image display process is omitted ofexplanation.

When the shutter button 38 is pressed in a state that the successivepicture-taking mode is off, the CPU 32 instructs the TG 14 to performall-pixel reading. The TG 14 drives the CCD imager 12 by theall-pixel-reading scheme thereby outputting one-screen camera signalscorresponding to a subject image from the CCD imager 12. The outputcamera signal is inputted to the signal processing circuit 20 throughthe CDS/AGC circuit 16 and A/D converter 18.

In the signal processing circuit 20, a main image signal is produced onthe basis of the input camera signal wherein, in the thinning-outcircuit 20 a, a thumbnail image signal is produced from the main imagesignal. That is, the thinning-out circuit 20 a performs vertical andhorizontal thinning-out processing on the main image signal therebyproducing a thumbnail image signal. The signal processing circuit 20outputs the produced main image signal and thumbnail image signal,together with a write request, to the memory control circuit 22. Themain image signal and the thumbnail image signal are respectivelywritten to the main image area 24 a and the thumbnail image area 24 b ofthe SDRAM 24 by the memory control circuit 22.

The CPU 32 first instructs, in timing of securing the main image signaland thumbnail image signal within the SDRAM 24, the JPEG CODEC 30 tocompressed the main image signal. The JPEG CODEC 30 requests, inresponse to this instruction, the memory control circuit 22 to read outa main image signal and performs JPEG compression on a main image signalread out of the main image area 24 a by the memory control circuit 22.Obtaining a compressed main image signal, the JPEG CODEC 30 instructsthe memory control circuit 22 to write the compressed main image signal.The compressed main image signal is thus written to the compressed imagearea 24 c of the SDRAM 24 by the memory control circuit 22.

The CPU 32 subsequently instructs the JPEG CODEC 30 to compress thethumbnail image signal. Consequently, the thumbnail image signal is alsoprocessed similarly to the above. That is, the thumbnail image signalsecured in the thumbnail image area 24 b is read out by the memorycontrol circuit 22 and subjected to JPEG compression by the JPEG CODEC30. Then, the produced compressed thumbnail image signal is stored tothe compressed image area 24 c by the memory control circuit 22.

After obtaining both the compressed main image signal and the compressedthumbnail image signal in this manner, the CPU 32 instructs the memorycontrol circuit to prepare an image file. The memory control circuit 22prepares an image file conforming to DCF, in response to thefile-preparing instruction. In the image file, the compressed main imagesignal and the compressed thumbnail image signal will be accommodated.The CPU 32 further sends to the memory control circuit 22 a request toread out this image file and then fetches a read image file read by thememory control circuit 22. The fetched image file is recorded onto thememory card 34.

When the shutter button 38 is pressed in a state that the successivepicture-taking mode is on, the CPU 32 processes a flowchart shown inFIG. 4. At first, in step S31 the count value N of the counter 32 a isset to “1”. Then, in step S33, the TG 14 is instructed to performall-pixel reading. The TG 14 drives the CCD imager 12 by the all-pixelreading scheme and outputs one-screen camera signals from the CCDimager. That is, a subject is taken once due to one instruction ofall-pixel reading so that a camera signal corresponding to the a subjectimage thus taken is outputted from the CCD imager 12. The output camerasignal is processed similarly to the above, and the corresponding mainimage signal and the thumbnail image signal are stored respectively inthe main image area 24 a and the thumbnail image area 24 b of the SDRAM24.

The CPU 32 advances, in timing of securing the main image signal andthumbnail image signal to the SDRAM 24, to step S35 where it instructsthe JPEG CODEC to compress the main image signal. The JPEG CODEC 30instructs, in response to the compression instruction, the memorycontrol circuit 22 to read out a main image signal and performs JPEGcompression on a main image signal read out of the main image area 24 aby the memory control circuit 22. Obtaining a compressed main imagesignal, the JPEG CODEC 30 requests the memory control circuit 22 towrite this compressed main image signal. The compressed main imagesignal is thus written to the compressed image area 24 c of the SDRAM 24by the memory control circuit 22.

The CPU 32 advances, in timing of storing the compressed main imagesignal to the SDRAM 24, to step S37 where it compares the current countvalue N with a predetermined value M. If N<M, the counter 32 a in stepS39 is incremented and then the process returns to the step S33.Consequently, a series of processes of steps S33 to S39 are repeateduntil the count value N reaches M. At a time of reaching the count valueN=predetermined value M, thumbnail image signals in the number of M areobtained within the thumbnail image area 24 b and compressed main imagesignals in the number of M are within the compressed image area 24 c.

If “YES” is determined in the step S37, the CPU 32 in step S41 sets thecount value N again to “1” and subsequently, in step S43, instructs JPEGCODEC 30 to compress a thumbnail image signal corresponding to thecurrent count value N. The JPEG CODEC 30 instructs the memory controlcircuit 22 to read out an Nth-produced thumbnail image signal andperforms JPEG compression on a thumbnail image signal read out of thethumbnail image area 24 b by the memory control circuit 22. The JPEGCODEC 30 further requests the memory control circuit 22 to write theproduced compressed thumbnail image signal. Due to this, the compressedthumbnail image signal is written to the compressed image area 24 c.

The CPU 32 thereafter, in step S45, sends a file preparing instructionto the memory control circuit 22. The memory control circuit 22prepares, in response to this instruction, an image file conforming toDCF in the compressed image area 24 and accommodates an Nth compressedmain image signal and compressed thumbnail image signal in this imagefile. In the following step S47, it is determined whether the currentcount value N is equal to the predetermined value M. If “NO”, thecounter 32 a in step S47 is incremented and then the process returns tothe step S43. The process of the steps S43 to S47 is repeated M times.As a result, image files in the number of M accommodating therein themutually-corresponded compressed main image signals and compressedthumbnail image signals within the compressed image area 24 c.

When the count value N reaches the predetermined value M, the CPU 32advances to step S51 where it performs a record process for the imagefiles in the number of M stored in the SDRAM 24. That is, the memorycontrol circuit 22 is requested to read out an image file and records animage file read out by the memory control circuit 22 onto the memorycard 34. Such a process is repeated M times, thereby recording all theimage files in the number of M to the memory card 34. Completing therecording process, the CPU returns to the main routine (not shown).

According to this embodiment, each time the image sensor takes onepicture, a main image signal and thumbnail image signal is produced andthe main image signal is compressed. At a time of ending successivepicture taking, compressed main image signals in the number M andthumbnail image signals in the number of M are secured within thememory. The compression process on the thumbnail image signals isperformed after ending the successive picture taking, thereby providingcompressed thumbnail image signals in the number of M.

In this manner, no compression process is done for the thumbnail imagesignals between the picture taking in the present time and the picturetaking in the next time. That is, the compression process of thumbnailimage signals, conventionally made between picture taking operations, ispostponed up to the end of successive picture taking. This reduces thetime interval of taking pictures. Also, compressing the main imagesignal between taking pictures reduces the internal memory capacity.

Incidentally, although the above embodiment takes picture of a subjectby the CCD-type image sensor, it is needless to say that a CMOS-typeimage sensor may be used in place thereof. Also, although in theembodiment the image-file recording medium used a semiconductor memory,it is needless to say that a disk recording medium may be used in placethereof.

Although the present invention has been described and illustrated indetail, it is clearly understood that the same is by way of illustrationand example only and is not to be taken by way of limitation, the spiritand scope of the present invention being limited only by the terms ofthe appended claims.

1. A digital camera which records, in a coded state, a plurality offrames of main image data and a plurality of frames of size-reducedimage data which are obtained by successive picture-taking operations toa recording medium, comprising: a main image coder for coding a singleframe of main image data every time a single picture-taking operation iscarried out so as to create a single frame of coded main image datawhich is reduced in a data amount prior to the taking of the nextsuccessive picture; a main image writer for writing the single frame ofcoded main image data to an internal memory every time a single codingoperation is carried out by said main image coder; and a size-reducedimage coder for coding the plurality of frames of size-reduced imagedata after ending the successive picture taking operations, wherein saidmain image coder adopts a JPEG format as a coding format.
 2. A digitalcamera according to claim 1, further comprising: a size-reduced imagecreator for respectively creating the plurality of frames ofsize-reduced image data based on a plurality of frames of the coded mainimage data held by said internal memory after ending the successivepicture taking operations, wherein said size-reduced image coder codesthe plurality of frames of size-reduced image data created by said sizereduced image creator.
 3. A digital camera according to claim 2, whereinsaid size-reduced image creator includes a decoder to decode theplurality of frames of coded main image data held by said internalmemory so as to create a plurality of frames of decoded main image data,and a thinner to perform thinning out on the plurality of frames ofdecoded main image data so as to create the plurality of frames ofsize-reduced image data.
 4. A digital camera according to claim 1,further comprising: a size-reduced image creator for creating a singleframe of size-reduced image data every time the single picture-takingoperation is carried out; and a size-reduced image writer for writingthe single frame of size-reduced image data to said internal memoryevery time a single creating operation is carried out by saidsize-reduced image creator, wherein said size-reduced image coder codesthe plurality of frames of size-reduced image data held by said internalmemory after ending the successive picture taking operations.
 5. Adigital camera which records, in a coded state, a plurality of frames ofmain image data and a plurality of frames of size-reduced image datawhich are obtained by successive picture-taking operations to arecording medium, comprising: a main image coder for coding a singleframe of main image data every time a single picture-taking operation iscarried out so as to create a single frame of coded main image datawhich is reduced in a data amount prior to the taking of the nextsuccessive picture; a main image writer for writing the single frame ofcoded main image data to an internal memory every time a single codingoperation is carried out by said main image coder; and a size-reducedimage coder for coding the plurality of frames of size-reduced imagedata after ending the successive picture taking operations, wherein bothof the main image data to be coded by said main image coder and thesize-reduced image data to be coded by said size-reduced image coder aredigital image data.